Posts Tagged ‘cogeneration’
Effective Use of Trigeneration in Australia
Posted in Models by Kate Archdeacon on May 11th, 2011
Source: Green Buildings Alive via Sustainable Cities Collective
Investa’s Trigen Image via The Fifth Estate
From “Australia’s first trigeneration ‘precinct’ is up and running!” by Craig Roussac:
[...] Sydney now has its first trigeneration precinct, where one building’s engine can power another one’s energy needs. Why was it necessary? To answer that question, let’s clarify a couple of things. First, when we say trigeneration we’re really describing a more elaborate form of cogeneration or combined heat and power (CHP). Cogeneration describes a system where the waste heat from a natural gas-powered engine that generates electricity is captured and used on-site. In instances where that waste heat (thermal energy) is directed through an absorption chiller to generate cooling, the system is referred to as trigeneration. Using gas as a fuel offers a significant reduction in carbon emissions when compared to coal-fired power generation, and the heat reclaim adds to the system efficiency. Sounds good, doesn’t it? As always, the devil is in the detail – particularly in warm climates such as those enjoyed by most Australians.
It goes without saying that electricity is almost always useful in buildings, wherever you are. Heat, on the other hand, is useful for much of the year in cold climates, but its benefits are greatly reduced in mild climates such as the one we’re blessed with in Sydney. The obvious solution for warm-weather situations where you don’t need much heat is to convert it into another form of thermal energy known as “coolth”. Hence the popularity of ‘trigeneration’ in this part of the world.
Investa installed a trigeneration plant along with a host of other environmentally-friendly features at its new 6-star office development, Coca-Cola Place in North Sydney. Ideally such plants are designed and operated to strike a balance between electrical loads and thermal loads. That is to say, you want to run the generator for extended periods at peak efficiency and have sufficient demand for thermal energy to take up all the waste heat from the electricity generation process.
Reciprocating gas engines need to be heavily loaded. If the electrical load drops below 60-70% the engine has to stop. If there isn’t demand for all the waste heat, you merely have a gas ‘generator’, not co- or trigeneration. What Investa found was that efficiency measures which were driving down electricity demand were compromising the efficient operation of the plant. It was sitting idle almost all the time. Because the base building is operating so efficiently, even with increased demand for electricity during warm weather (due to air-conditioning) the problem didn’t go away because the electrical load would drop right off whenever the absorption chiller kicked in. There was simply no way to run the building efficiently and also operate the trigeneration plant. This appears to be the choice faced by many owners of trigeneration plants.
Investa’s solution was to lease the building’s entire Energy Centre (plant room) to a specialist operator and enter into two 12-year energy supply agreements to round out the package. The arrangement links the Coca-Cola building and Deutsche Bank Place via the electricity grid. Because Investa’s partners, Cogent and Origin, are licensed electricity retailers, they are able to manage the electrical loads between the two buildings on the National Electricity Market. Effectively the system now services an electrical load of a combined 70,000 sqm highly efficient building coupled to the thermal load of a 28,000 sqm building. This is sufficient to allow for daily and seasonal fluctuations in energy demand while still allowing the plant to run efficiently for up to 14 hours per day. Most of the thermal energy will now be captured and used efficiently most of the time.
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Read the full article by Craig Roussac for Green Buildings Alive.
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Shared Cogeneration Project: Queensland
Posted in Models by Kate Archdeacon on May 26th, 2010
Source: Green Building Council Australia (GBCA)
From “Co-gen in Queensland: green tick from gas supplier a positive sign for precincts” by Lynne Blundell
There could be light at the end of the tunnel for cogeneration projects seeking co-operation from energy agencies. In a victory for precinct-style power generation, a proposed shared cogeneration project between The University of Queensland and the Royal Brisbane Hospital has received support from gas suppliers. It was very much an industry-driven victory. After an initial knock-back by gas suppliers to support the project, sustainability consultants from Cundall, armed themselves with extensive technical data to back their case. But it took some political nous as well – this time they bypassed the technical people and went straight to the top.
Cundall’s Brisbane head, Rob Lord, told The Fifth Estate the decision by the gas authority to fund the necessary infrastructure to supply gas to the shared power plant was a sign of a shift in attitudes. “It is a kind of awakening for these authorities. They are bureaucracies and are very focused on risk. What we want is for them to be not only conscious of the risk but also the opportunities of cogeneration and shared energy schemes,” says Lord. “When the gas company was first approached they said it couldn’t be done. But when we got back to the upper echelons of the company with all the mechanical, hydraulic and sustainability information they were very positive about the opportunities and they told their technical people they wanted it to happen.”
With cogeneration, and trigeneration, buildings can generate their own power from gas-fired generators, reduce their reliance on the electricity grid and use waste heat to help cool and heat a building. But resistance from energy agencies to these plants putting energy back into the grid or to providing the necessary infrastructure for projects has been a major disincentive for developers and building owners considering the technology.